This is a note to let you know that I've just added the patch titled
NFSD: Add a mechanism to wait for a DELEGRETURN
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-add-a-mechanism-to-wait-for-a-delegreturn.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e5ebaea1b1a7e8b6eea62353d1e074c437d2ee83
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu Sep 8 18:14:00 2022 -0400
NFSD: Add a mechanism to wait for a DELEGRETURN
[ Upstream commit c035362eb935fe9381d9d1cc453bc2a37460e24c ]
Subsequent patches will use this mechanism to wake up an operation
that is waiting for a client to return a delegation.
The new tracepoint records whether the wait timed out or was
properly awoken by the expected DELEGRETURN:
nfsd-1155 [002] 83799.493199: nfsd_delegret_wakeup: xid=0x14b7d6ef fh_hash=0xf6826792 (timed out)
Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a0c5658599ead..6cb654e308787 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4734,6 +4734,35 @@ nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type)
return ret;
}
+static bool nfsd4_deleg_present(const struct inode *inode)
+{
+ struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx);
+
+ return ctx && !list_empty_careful(&ctx->flc_lease);
+}
+
+/**
+ * nfsd_wait_for_delegreturn - wait for delegations to be returned
+ * @rqstp: the RPC transaction being executed
+ * @inode: in-core inode of the file being waited for
+ *
+ * The timeout prevents deadlock if all nfsd threads happen to be
+ * tied up waiting for returning delegations.
+ *
+ * Return values:
+ * %true: delegation was returned
+ * %false: timed out waiting for delegreturn
+ */
+bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp, struct inode *inode)
+{
+ long __maybe_unused timeo;
+
+ timeo = wait_var_event_timeout(inode, !nfsd4_deleg_present(inode),
+ NFSD_DELEGRETURN_TIMEOUT);
+ trace_nfsd_delegret_wakeup(rqstp, inode, timeo);
+ return timeo > 0;
+}
+
static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
{
struct nfs4_delegation *dp = cb_to_delegation(cb);
@@ -6797,6 +6826,7 @@ nfsd4_delegreturn(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
if (status)
goto put_stateid;
+ wake_up_var(d_inode(cstate->current_fh.fh_dentry));
destroy_delegation(dp);
put_stateid:
nfs4_put_stid(&dp->dl_stid);
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 57a468ed85c35..6ab4ad41ae84e 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -164,6 +164,7 @@ char * nfs4_recoverydir(void);
bool nfsd4_spo_must_allow(struct svc_rqst *rqstp);
int nfsd4_create_laundry_wq(void);
void nfsd4_destroy_laundry_wq(void);
+bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp, struct inode *inode);
#else
static inline int nfsd4_init_slabs(void) { return 0; }
static inline void nfsd4_free_slabs(void) { }
@@ -179,6 +180,11 @@ static inline bool nfsd4_spo_must_allow(struct svc_rqst *rqstp)
}
static inline int nfsd4_create_laundry_wq(void) { return 0; };
static inline void nfsd4_destroy_laundry_wq(void) {};
+static inline bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp,
+ struct inode *inode)
+{
+ return false;
+}
#endif
/*
@@ -343,6 +349,7 @@ void nfsd_lockd_shutdown(void);
#define NFSD_COURTESY_CLIENT_TIMEOUT (24 * 60 * 60) /* seconds */
#define NFSD_CLIENT_MAX_TRIM_PER_RUN 128
#define NFS4_CLIENTS_PER_GB 1024
+#define NFSD_DELEGRETURN_TIMEOUT (HZ / 34) /* 30ms */
/*
* The following attributes are currently not supported by the NFSv4 server:
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 56b6c3f61d5ea..d073b905e54e7 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -538,6 +538,29 @@ DEFINE_NFSD_COPY_ERR_EVENT(clone_file_range_err);
#include "filecache.h"
#include "vfs.h"
+TRACE_EVENT(nfsd_delegret_wakeup,
+ TP_PROTO(
+ const struct svc_rqst *rqstp,
+ const struct inode *inode,
+ long timeo
+ ),
+ TP_ARGS(rqstp, inode, timeo),
+ TP_STRUCT__entry(
+ __field(u32, xid)
+ __field(const void *, inode)
+ __field(long, timeo)
+ ),
+ TP_fast_assign(
+ __entry->xid = be32_to_cpu(rqstp->rq_xid);
+ __entry->inode = inode;
+ __entry->timeo = timeo;
+ ),
+ TP_printk("xid=0x%08x inode=%p%s",
+ __entry->xid, __entry->inode,
+ __entry->timeo == 0 ? " (timed out)" : ""
+ )
+);
+
DECLARE_EVENT_CLASS(nfsd_stateid_class,
TP_PROTO(stateid_t *stp),
TP_ARGS(stp),
